<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>factorial</title>
</head>

<body>
    <div>打开浏览器控制台查看结果</div>
    <script>
        const factorial = n =>
            n < 0
                ? (() => {
                    throw new TypeError('Negative numbers are not allowed!');
                })()
                : n <= 1
                    ? 1
                    : n * factorial(n - 1);
        console.log(factorial(6));
    </script>
</body>

</html>